By Amy Norton NEW YORK (Reuters Health) - The body's sensitivity to a
particular brain chemical may help separate those of us who
can't sit still from those who can't seem to get off the couch,
a study in rats suggests.

Researchers at the University of Pennsylvania School of Medicine have discovered that the recently identified neurotransmitter orexin (also known as hypocretin) influences reward processing by activating neurons in the lateral hypothalamus region of the brain. By identifying the relationship between orexin neurons and behaviors associated with reward seeking, drug relapse, and addiction, researchers hope to find new treatments for drug addiction.

A pivoted catch designed to fall into a notch on a ratchet wheel so as to allow movement in only one direction (e.g. on a windlass or in a clock mechanism), or alternatively to move the wheel in one direction.